In a process of manufacturing glass sheet products as typified by glass substrates for a plasma display panel (PDP), a field emission display (FED), an electroluminescent display (ELD), and the like, a small-area glass sheet is cut out of a large-area glass sheet and an edge portion extending along each side of the glass sheet is trimmed off. As a method therefor, a method of cleaving a glass sheet is taken as an example.
In this case, a laser cleaving method is taken as one method of cleaving a glass sheet, and for example, this technology is disclosed in Patent Literature 1 described below.
Patent Literature 1 discloses a technology of cleaving a glass sheet by the laser cleaving method in the following manner. That is, an absorption coefficient of the glass sheet for a laser beam is controlled, and the laser beam is caused to pass through a material in a range of the overall thickness thereof, or to pass through the material in a range of up to a sufficient depth even when the laser beam is not caused to pass in the range of the overall thickness. Accordingly, an initial crack formed in an end surface of the glass sheet propagates due to a thermal stress in the range of the overall thickness of the glass sheet.
According to the technology disclosed in Patent Literature 1 described above, the positional accuracy of the cleaving can be enhanced and the cleaving speed can be increased. Thus, this technology produces various advantages as compared to a conventional method of mechanically cleaving a glass sheet through use of a diamond cutter or the like.